In order to deliver a medicine which a medicine ejection apparatus, such as an inhaler, ejects to an objective site effectively, the ejection droplet diameter and the user's respiratory behavior are important factors. For both the ejection droplet diameter and respiratory behavior, there are conditions suitable for each according to the site to which a medicine is to be delivered. Thus, in inhalation treatment, the curative effect is dependent on how the user inhales.
In Japanese Publication of PCT International Application No. H10-507096, it is described that inhalation which has a high lung deposition rate and good efficiency can be achieved by ejecting an aerosolized medicine within a range of determined inhalation flow rate and inhalation amount. The inhalation apparatus disclosed in Japanese Publication of PCT International Application No. H10-507096 can be controlled so as to start ejection of the medicine when the user's inhalation flow rate reaches a predetermined value, and to stop the ejection of the medicine when it reaches a certain predetermined inhalation amount.
In addition, in Japanese Publication of PCT International Application No. 2006-506151, a technique of registering a user's inhalation pattern and spraying in accordance with the pattern is disclosed as a means of causing liquid droplets to be inhaled in a proper inhalation profile. According to this technique, spraying can be synchronized in pulsed manner with breathing by measuring beforehand a user's breathing pattern and recording the information in the inhaler. On the other hand, an inhalation apparatus has been developed, which produces minute liquid droplets of a medicine ejected into an air current path, through which air inhaled through a mouthpiece flows, using the ejection principle of an ink jet system to make a user inhale them (refer to Japanese Patent Application Laid-Open No. 2004-283245). Such inhalation apparatuses have an advantage of being able to spray a predetermined amount of medicine precisely with an equalized particle diameter.
In the inhalation apparatuses described in the above-mentioned background art, even if the inhalation parameters are suitable at the beginning or start of spraying, the subsequent inhalation might not be appropriate. However, it is not expectable that a user inhales precisely the same way each time, and when a medicine is released only while a suitable inhalation profile is achieved, there is no guarantee that the whole dose can be administered by one time of inhalation. For example, when a user stops inhalation for a certain reason in the middle of inhalation, a possibility of an ejection amount of medicine not reaching the dose is high.
Accordingly, in the conventional inhalation apparatuses, it cannot be said that quantitative control can be performed since it is not possible to tell whether the user has inhaled the full dose of the medicine.